The subject invention is directed toward the valve art and, more particularly, to valves having improved operators. The invention is particularly suited for use in bellows type valves and will be described with particular reference thereto; however, as will be appreciated, the invention is capable of broader application and could be incorporated in many different types of valves.
Corrugated bellows members formed from metal provide a highly efficient method of sealing valve chambers. Bellows sealed valves are well known and widely used when hermetically sealing and/or the elimination of mechanical seals is desired.
Typically, the metal bellows members used for valve sealing have a long life. Generally they are capable of undergoing a very large number of operating cycles so long as they are subjected to only axial extension and contraction and are not also subjected to torque.
When bellows sealed valves are actuated through the use of air cylinders or similar linear motion devices, torque problems are not present. However, when using rotary actuators such as a rotary threaded operating stem, torque transmission to the bellows becomes a problem. Similarly, problems can be encountered with other actuators such as certain toggle and lever actuators.
Many different solutions have been proposed for eliminating the various problems discussed above. For example, a variety of pinned, non-torque transmissive joints have been used. These are illustrated, for example, in U.S. Pat. Nos. 1,906,313, 3,278,156 and 3,491,789. Generally, however, these prior arrangements transmit some torque and typically have an undesirable amount of backlash.